Where is the end of extending the range of electric bass ?

I'm very interested in the whole extended range thing and I wondered where is the end of adding more and more strings.
There are 9-strings at the moment but I personally dream of a non-doubled 12-string tuned:

C# F# B E A D G C F Ab D# G#

Would this be possible on a 34.5" scale speaking of string gauges and so on ?
What would you have to keep in mind when building such a monster ?

First off, its not likely that such and instrument will be built anytime soon.

Main issues as I see them are neck strength and string gauge.

Its actually the smaller strings which exert the most force on the neck, and adding so many higher strings will cause an incredible amount of stress. Its not an amount that cant be dealed with, but it may require that he neck be quite large to support the tensions.

Finding strings that small is going to be difficult. I cant imagine that anyone will be able to make strings that will be able to be brought to tension on notes that high without snapping.

The low strings are not the easiest to deal with, but we all know that it has been done.

Its been done before but I doubt that the bass was 34.5" scale. If you go to http://www.acaciainstruments.com you can see a pic. of a 9 string bass. They are out of business now but my teacher plays an Acacia and he says that that bass has I think a 13 piece neck. Its in the raves section.

The original poster was not asking about a 9-string bass, which he acknowledged had already been done--the Acacia being only one example along with Warrior, Conklin, and otehrs. He was asking about a 12-string bass, which hasn't ever been done to my knowledge...though I seem to recall hearing something about Bill Dickens having an 11-string Conklin built. I could be remembering it wrong though (I get lost after 7 or so).